1. Field of the Invention
This invention relates to an optical information recording/reproduction apparatus for optically recording and reproducing information by using a light beam.
2. Description of the Prior Art
An optical information recording/reproduction apparatus is capable of recording information based on a reduced size of a light spot formed on a recording medium by irradiating the recording medium with a light beam through an optical system and is therefore advantageous in increasing the recording density. A conventional apparatus of this kind constructed as an opto-magnetic information recording/reproduction apparatus will be described below.
As shown in FIGS. 1 and 2, a conventional optical information recording/reproduction apparatus has a cartridge insertion opening 3 which can be closed by a shutter and which is formed in a portion of a drive case 1. A disk cartridge 5 including a recording medium is inserted into or ejected out of the drive case 1 through the opening 3. A spindle motor 6 and a turntable 6a driven by the spindle motor 6 are provided in the drive case 1 to rotate the disk cartridge 5 at a constant speed. The disk cartridge 5 is fixed on the turntable 6a by a clamp means 6b such as a magnetic clamp. An optical head 8 for recording/reproducing information is disposed in the drive case 1. The optical head 8 is operated and controlled by a drive unit 12 moved in a radial direction of the recording medium. An optical system of such an apparatus includes a movable optical system provided on the optical head 8, and is constituted by an objective lens and a movable mirror (not shown). The optical system also includes a fixed optical system 9 which includes a laser provided as a light source and a detector (not shown) for detecting light reflected from the recording medium, and which is fixedly disposed on the apparatus opposite to the movable optical system. A magnetic field bias applying means 10 for applying a magnetic field bias to the recording medium is also provided in the drive case 1. The magnetic field bias applying means 10 applies a recording or erasing basing magnetic field to the recording medium at a position where the recording medium is irradiated with a light beam from the optical head 8. In the drive case 1 are further provided electric circuit boards including printed control circuit boards 11 on which are formed a circuit 7 for driving the spindle motor 6, a circuit (not shown) for controlling the magnetic field bias applying means 10 which opposes the optical head 8, a servo circuit (not shown) for controlling the state (e.g., tracking or focusing) of the light beam emitted from the optical head 8 and other circuits, and a circuit 15 for driving the optical head 8.
As shown in FIGS. 1 and 2, these components are housed as a unit in a container 2 placed in the drive case 1. The container 2 is supported on the drive case 1 by a vibration damping mechanism (not shown). A power source 13 for driving the above-noted components is separately provided in the drive case 1. A cooling fan 14 is provided on the drive case 1 to introduce air for cooling the power source 13 and then for directly cooling heating members as desired while causing air to flow to an air outlet 4 through ventilation openings 2a and 2b formed in walls of the container 2, as shown in FIG. 1, or the air directly cools the power source 13 after being introduced by the cooling fan 14, and indirectly cools the heating members in the container 2 by cooling outside walls of the container 2 while flowing through gaps between the container 2 and the drive case 1, as shown in FIG. 2. This cooling is intended to prevent damage to the information on the recording medium or deterioration of the performance of each of the semiconductor lasers serving as light sources and other electric parts due to an increase in the temperature in the drive case 1 or in the container 2 caused by the heat from the heating members in the container 2 of the apparatus.
In the former of these arrangements, as shown in FIG. 1, the heating members can be cooled by the cooling air introduced into the container 2, but there is a risk that any dust contained in the air will adhere to the optical system of the optical head and to the surface of the recording medium and, hence, will hinder correctly recording or reproducing information. In the case of the latter of these arrangements, as shown in FIG. 2, the heat sources, i.e., the spindle motor, the drive circuit, the light source of the fixed optical system, the printed control circuit board, and so on cannot be cooled sufficiently.
It is essential to efficiently cool the spindle motor, the drive circuit (for the light source and the spindle motor) and the printed control circuit boards, which are the primary heat sources.